What is High pass filter: Definition and 30 Discussions

A high-pass filter (HPF) is an electronic filter that passes signals with a frequency higher than a certain cutoff frequency and attenuates signals with frequencies lower than the cutoff frequency. The amount of attenuation for each frequency depends on the filter design. A high-pass filter is usually modeled as a linear time-invariant system. It is sometimes called a low-cut filter or bass-cut filter in the context of audio engineering. High-pass filters have many uses, such as blocking DC from circuitry sensitive to non-zero average voltages or radio frequency devices. They can also be used in conjunction with a low-pass filter to produce a bandpass filter.
In the optical domain, high-pass and low-pass are often characterized by wavelength instead of frequency, with a "high-pass" filter (or "short-pass") passing only shorter wavelengths (higher frequencies), and vice versa for "low-pass" (or "long-pass").

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  1. ARoyC

    High Pass Filter Working Principle

    A few days ago, I learned to make an AC to DC converter. One question is troubling my mind. How does a High Pass Filter Capacitor work? Going through some websites I got a sketchy idea. As the current after passing through the bridge rectifier comes to capacitor, the capacitor starts charging...
  2. D

    Confusion on: High Pass Filter at Op Amp Input

    Hello, I am simulating the input impedance of a high-pass filter with the output voltage of the filter input to the non-inverting pin of an op amp. I'm confused as to why the input impedance can possibly dip below the resistance of the high-pass filter resistor. Please see the following circuit...
  3. W

    Third Order High Pass Filter (Report)

    Homework Statement [/B] The filters of FIGURE 4(a) to (c) where designed using a commercial software package (http://focus.ti.com/docs/toolsw/folders/print/filterpro.html) Write a report (of approximately 750 words) that discusses and compares the design of each filter in terms of their...
  4. Abdul Wali

    Design of High Pass filter to eliminate an instability in my control system

    HI, i have a first order controller (ts/ks+k) which contain some oscillations and its settling time is very huge, i wanted the controller to have settling time of 10seconds and remove the oscillations. in order to remove the noise and get the expected settling time i added a filter ( s/cs+1)...
  5. T

    What is the design and performance comparison of third order high pass filters?

    Homework Statement Write a report (of approximately 750 words) that discusses and compares the design of each filter in terms of their performance, circuit topology, application and any other relevant characteristics. You may for example attempt to relate the choice of component values to the...
  6. T

    Simulation with Spice to get coil and caps values

    Hi, as I am in need of Low- and Highpass filters i would like to simulate my circuit using LT-Spice. I hope that i can get optimal caps and coils values like that. So i simply started to build my pi-network lowpass filter in LT-Spice and got the simulation results (please check the picture in...
  7. DeldotB

    High pass filter response at high frequencies

    Good day all, I have a question: I built a passive high pass filter in an experiment using a hand wound inductor (toriod) and a resistor. The filter worked great as a high pass at frequencys ranging from 100 Hz - 1,000,000 Hz (rolling off around 10,000 Hz). After creating a bode plot, I...
  8. G

    Why resistor between +input and ground necessary in OP-AMP?

    Hello. Please see the attached image first. 1. The textbook seems say resistor to + input in this image is necessary to provide a return path to ground. I completely don't understand even what it mean. Could you help me to clarify this? 2. Instead of understanding directly what the book said...
  9. S

    Converting a 50kHz high pass filter to a 5.3kHz HP filter

    Homework Statement Converting a 50kHz high pass filter to a 5.3kHz high pass filter. The circuit: Homework Equations Working out the Capacitance, C, and Resistance, R, of the circuit in order to work out the cut-off frequency, Cf, using: Cf = 1/(2*pi*R*C)[/B] The Attempt at a Solution...
  10. C

    Filter shape from poles and zeros

    Hey guys, I am learning about the filter shapes deduced from the poles and zero plots, however a lot of sources are describing it differently with no logical explanation. I want to know what exactly the poles and zeros do between the range Ω = 0 and Ω = π. One source i read explains if the pole...
  11. R

    Engineering Where is the bandpass filter in this circuit?

    Homework Statement I am doing a project on the Elenco AM/FM superheterodyne radio kit. I have been stuck for ages trying to figure out how the two common emitter amplifiers are tuned to filter out anything that is not around 455 kHz. I tried to find a bandpass filter, or a high-pass and a...
  12. A

    High Pass Filter Design: Reduce Interference to 0.05V Peak

    1. Homework Statement ''A machineoutputs a 4kHz sine wave signal of amplitude 2 volts peak, plus a 100Hz interference component of amplitude 1 V peak'' Given equation: Vout/Vin = 1/((1+(f0/f^2))^0.5 phase lead = inverse tan (f0/f) f0 = 1/(2*pi*R*C)I'm given a 4 kilo-ohm resistor and need to...
  13. K

    Can I Convert My Bode Plots to Logarithmic Scale in Excel?

    Got excel spreadsheet. in my excel worksheet "4" i plot bode plot for low and high pass. Our lab experiement aim was measure two set of data and identify which one is low pass and which one is highpass filter. But as soon as I am trying to put lograitham graph it is not allow me ? I...
  14. E

    Unit step response of RC high pass filter

    what is the unit step response of a high pass RC filter ? I want to calculate using transfer function approach. My solution : Y(s)/X(s) = RCs/(1+sRC) X(s)=1/s Y(s)=RC/(1+sRC) taking inverse laplace transform we should get y(t)=exp(-t/RC) But if we consider Y(s)=RC/(1+sRC) RCsY(s)...
  15. A

    How does a high pass filter work?

    "The simplest high pass filter is a capacitor in resistor in series, where the voltage across the capacitor is used as output." Quote wikipedia The picture of this simple high pass filter is found at: http://upload.wikimedia.org/wikipedia/commons/f/fe/High_pass_filter.svg. I wonna get some...
  16. X

    Using Thevenin's theorem on a High pass filter with a DC Offset

    Homework Statement A 1kHz square wave with an amplitude of 2V (peak to peak) is applied at the input V-in of the circuit shown. The resistor R1 = R2 = 10 kΩ, and C = 0.02 μF. a) What is the effective time constant of this circuit? b) What is the minimum and maximum voltage reached at...
  17. D

    Understanding High Pass Filter: Plate Behavior and Phase Shift

    I'm having a hard time visualizing what happens on the plates of the capacitor in series with a resistor in a high pass filter circuit. When the input to the capacitor is high, assuming a sine wave (say +5V) what happens on the opposite plate of the capacitor (Vout)? Should the output follow the...
  18. D

    High pass filter, output has negative voltage level

    I built a clock generator using a 555 and I fed the output to a high pass filter. It works for the most part, BUT the input voltage ranges from 0 to 5V while the output is -5 to 0 V. I can't figure out why this is happening. I'm new to EE, so bear with me.
  19. G

    High pass filter and low pass filter question?

    You have a series circuit consisting of a ac power supply, a 1150.0 ohm resistor and a 144.0 nF capacitor. If the circuit is configured as a low pass filter, what frequency will cause the gain to be 0.25? Formula Gain = Vout / Vin = R / [R^2 + (1/ωC)^2]^1/2Solution Plugging in R=1150 ohms...
  20. J

    Transforming a low pass filer to a high pass filter

    Hi, I have trouble understanding how to achieve this transformation Suppose for example that we have a low pass filter which impulse response is the following h(n) = 1 for 0<=n<=2 where n is an integer In the frequency domain we would have the following frequency response: H(e^{j\omega}) =...
  21. D

    Phase constant for high pass filter

    Homework Statement If the input voltage is given by Vin = Vin peak cos ωt, then the output voltage is Vout = VH*cos(ωt - δ) where VH = Vin peak/(1 + (ωRC)^(−2)) (Assume that the output is connected to a load that draws only an insignificant amount of current.) Find an expression...
  22. jegues

    Deriving Corner Frequency for High Pass Filter

    Homework Statement See Explanation below for details of my confusion. Homework Equations The Attempt at a Solution Hello all, I've derived a transfer function, T(s) = \frac{\frac{-R_{2}}{R_{1}}}{1 + \frac{1}{sCR_{1}}}, but I can't seem to derive the corner frequency...
  23. D

    High Pass Filter: Help with 60Hz Source

    Hey everyone I have recently started a circuits class, and am enjoying it. However, the high pass filters have slightly confusing me. I recently set up a circuit that was straight from a wall socket meaning that it has a frequency of ~ 60 Hz. My high-pass filter should filter out all of the...
  24. L

    MATLAB 10Hz High Pass filter with Matlab

    Hi everyone, here is the problem: I am trying to reproduce a human finger while pressing a keyboard. I am using a shaker and a fingertip made of foam rubber. To measure the force history, a force gage make a link between the fingertip and the shaker. The fact is the curve has an offset and...
  25. A

    Engineering High Pass Filter RL circuit: Time/Frequency Response

    Homework Statement For circuit B on page 2, find: a) the time domain response v0 for a unit step input b) input/output transfer function T(s) = v0/v_in c) plot v0 vs. time d) plot sinusoidal steady state vs. frequency: the magnitude in dB and phase in degrees of T(s) Homework...
  26. G

    High Pass filter & Low Pass Filters features

    Hi I want your help to know what's the features of HPF and LPF, and their applications area? Thanks
  27. G

    High Pass Filter: R & C Transfer Function

    whats the transfer function of this simple High Pass filtre circut: if R = 10000 ohm C = 220 nF
  28. S

    Simple High Pass Filter Problem

    Homework Statement Given a simple RC high pass filter, I need to find the value of C that will give the output as shown on a scope capture. Input Voltage: 2.5 + 10.01cos(\omega t) (10.01V wave shifted up 2.5V) Output Voltage: 3.46cos(\omega t - 60^\circ) R = 5k \omega = 2\pi 100...
  29. J

    High pass filter for pulse shaping

    Hello All, I have been doing some experiments where I need to make a very short pulse to switch on and off a MOSFET I am using (IRF840) but all I have as a pulse source is a small function generator which outputs square waves fixed at 50% duty cycle. So I had an idea to use a simple high...
  30. B

    Help designing a RC passive high pass filter

    Homework Statement I was asked to desing a RC passive high pass fiilter with a cutoff of 3KhZ. Homework Equations The formula for Fc = 1/(2piRC) The Attempt at a Solution I set 3kHz = (1/(2piRC)) but am not sure what to do next. Do I pick a random cap or resistor value and...